I trying to work how to get a JAX-WS webservice deployed on JBoss AS 7.1 to send the full stack trace in a message response when that exception is not modeled (i.e. the service is throwing a runtime exception).

The faultStackTraceEnabled=true and exceptionMessageCauseEnabled=true properties are client side props, while the endpoint-config section of the ws subsystem model is of course for server side (endpoint) configuration.

The properties hand over to the cxf internals is working as the message has the the stacktrace in it, with the proper line numbers. What seems to be missing is the actual name of the exception that's been thrown. Is this what you're referring to / looking for?

I have just tried reverting JBoss-WS Native and have encountered a number of issues, I know you indicated that it isn't an easy fix but is there a hack? Could you give some indication of what needs to be built and deployed? If I know what jar needs building I might be able to implement the hack?

Regarding a possible hack, have a look at the description in https://issues.apache.org/jira/browse/CXF-4242 . You can hack AbstractSoapInterceptor::prepareStackTrace(..) to include the info you need, re-build Apache CXF (possibly using the tag of the version included in you AS as a base) and copy the new jars over those you have in modules/org/apache/cxf/main. However cxf clients are going to fail processing messages with the new fault detail because they do not expect the added info. So the client side also needs fixing, likely in most of the classes that have been touched when dealing with CXF-3445.